Methods and apparatus for zone control of RF bias for stress uniformity

Abstract

Methods and apparatus are used for adjusting film stress profiles on substrates. An apparatus may include a PVD chamber with a pedestal configured to support a substrate during processing on a cover positioned on an uppermost surface of the pedestal. The cover is constructed with multiple electrodes such as, for example, a first electrode, a second electrode, and a third electrode. The second electrode is positioned between and electrically separated from the first electrode and the second electrode. A substrate stress profile tuner is electrically connected to the first electrode, the second electrode, and the third electrode and configured to independently adjust an RF voltage level of at least the second electrode and the third electrode relative to RF ground to produce a more uniform film stress profile.

The invention claimed is: 
     
       1. An apparatus for adjusting film properties during deposition, comprising:
 a physical vapor deposition (PVD) chamber with a processing volume; 
 an upper electrode positioned in the PVD chamber above the processing volume and connected to a direct current (DC) power source, the DC power source configured to generate plasma within the processing volume; 
 a pedestal configured to support a substrate during processing in the PVD chamber and positioned below the processing volume, wherein the upper electrode is positioned parallel to an uppermost surface of the pedestal that supports the substrate; 
 a cover configured to support a substrate is positioned on an uppermost surface of the pedestal, wherein the cover includes a plurality of electrodes with circular shapes in the cover and arranged in expanding concentric circles about a center axis of the cover; 
 a substrate stress profile tuner electrically connected to each of the plurality of electrodes and configured to independently adjust an RF voltage level of at least one of the plurality of electrodes relative to RF ground; 
 an RF bias source electrically connected to the substrate stress profile tuner via a match network; and 
 a controller in communication with the substrate stress profile tuner and configured to automatically and independently adjust stress levels based on at least one stress profile at a plurality of annular or circular areas across a film as the film is deposited on the substrate. 
 
     
     
       2. The apparatus of  claim 1 , wherein the DC power source is a pulsed DC power source. 
     
     
       3. The apparatus of  claim 1 , wherein the PVD chamber includes a magnetron assembly configured with at least one rotating permanent magnet positioned above the upper electrode. 
     
     
       4. The apparatus of  claim 1 , wherein the pedestal is formed of a ceramic material and contains electrical connections between the plurality of electrodes and the substrate stress profile tuner. 
     
     
       5. The apparatus of  claim 1 , wherein the plurality of electrodes includes a first electrode, a second electrode, and a third electrode, and wherein the second electrode is positioned between and electrically separated from the first electrode and the second electrode and the substrate stress profile tuner is configured to independently adjust the RF voltage level of at least the second electrode and the third electrode relative to RF ground. 
     
     
       6. The apparatus of  claim 5 , further comprising:
 a first RF rod in the pedestal electrically connecting the first electrode to the substrate stress profile tuner; 
 a second RF rod in the pedestal electrically connecting the second electrode to the substrate stress profile tuner; and 
 a third RF rod in the pedestal electrically connecting the third electrode to the substrate stress profile tuner. 
 
     
     
       7. The apparatus of  claim 5 , wherein the substrate stress profile tuner is configured to independently adjust an RF bias voltage level of the first electrode, the second electrode, and the third electrode relative to RF ground. 
     
     
       8. The apparatus of  claim 5 , wherein the substrate stress profile tuner includes:
 a first tuning circuit positioned inside the substrate stress profile tuner and includes at least one first adjustable capacitor, wherein the first tuning circuit is electrically connected between the match network and the second electrode; and 
 a second tuning circuit positioned inside the substrate stress profile tuner which includes at least one second adjustable capacitor, wherein the second tuning circuit is electrically connected between the match network and the third electrode. 
 
     
     
       9. The apparatus of  claim 8 , further comprising:
 a first voltage sensor electrically positioned between the first adjustable capacitor and the second electrode; and 
 a second voltage sensor electrically positioned between the second adjustable capacitor and the third electrode. 
 
     
     
       10. The apparatus of  claim 8 , wherein the substrate stress profile tuner further includes:
 a third tuning circuit positioned inside the substrate stress profile tuner which includes at least one third adjustable capacitor, wherein the third tuning circuit is electrically connected between the match network and the first electrode. 
 
     
     
       11. The apparatus of  claim 10 , further comprising:
 a third voltage sensor electrically positioned between the third adjustable capacitor and the first electrode. 
 
     
     
       12. The apparatus of  claim 5 , wherein the first electrode has a disk shape, the second electrode has a first annular shape larger than the disk shape, and the third electrode has a third annular shape larger than the first annular shape. 
     
     
       13. The apparatus of  claim 1 , further comprising:
 a stress detector that is configured to determine at least one stress profile of at least one substrate, wherein the stress detector is in communication with the controller. 
 
     
     
       14. The apparatus of  claim 13 , wherein the stress detector is located in-situ in the PVD chamber or ex-situ from the PVD chamber. 
     
     
       15. An apparatus for adjusting film properties during deposition, comprising:
 a pedestal configured to support a substrate during processing in a PVD chamber and configured to be positioned below a processing volume of the PVD chamber wherein the pedestal has an uppermost surface that supports the substrate and is configured to be positioned with the uppermost surface parallel to an upper electrode of a plasma vapor deposition (PVD) process chamber when installed in the PVD process chamber; 
 a first electrode with a disk shape that is positioned in a central area of the pedestal proximate the uppermost surface of the pedestal, wherein the first electrode is configured to accept a first RF bias voltage adjustment from a substrate stress profile tuner; 
 a second electrode with a first annular shape that surrounds the first electrode proximate an uppermost surface of the pedestal and is electrically isolated from the first electrode, wherein the second electrode is configured to accept a second RF bias voltage adjustment from the substrate stress profile tuner; 
 a third electrode with a second annular shape that surrounds the second electrode proximate an uppermost surface of the pedestal and is electrically isolated from the second electrode, wherein the third electrode is configured to accept a third RF bias voltage adjustment from the substrate stress profile tuner; and 
 a controller in communication with the substrate stress profile tuner and configured to automatically and independently adjust stress levels based on at least one stress profile at a plurality of annular or circular areas across a film as the film is deposited on the substrate. 
 
     
     
       16. The apparatus of  claim 15 , wherein the first electrode, the second electrode, and the third electrode are electrically separated by an air gap or an electrically insulating material. 
     
     
       17. The apparatus of  claim 15 , further comprising:
 a first RF rod in the pedestal which is configured to electrically connect the first electrode to the substrate stress profile tuner; 
 a second RF rod in the pedestal which is configured to electrically connect the second electrode to the substrate stress profile tuner; and 
 a third RF rod in the pedestal which is configured to electrically connect the third electrode to the substrate stress profile tuner. 
 
     
     
       18. The apparatus of  claim 15 , further including:
 the substrate stress profile tuner electrically connected to the first electrode, the second electrode, and the third electrode and configured to independently adjust an RF voltage level of at least the second electrode and the third electrode relative to RF ground, and 
 wherein the substrate stress profile tuner includes:
 a first tuning circuit positioned inside the substrate stress profile tuner which includes at least one first adjustable capacitor, wherein the first tuning circuit is configured to be electrically connected to the second electrode; and 
 a second tuning circuit positioned inside the substrate stress profile tuner which includes at least one second adjustable capacitor, wherein the second tuning circuit is configured to be electrically connected to the third electrode.